Automatic telephone system.



a r? BEEN/7195a M/JLL/S V & 04% 7 vfimm B. D. WILLIS.

AUTOMATIC TELEPHONE SYSTEM. APPLICATION FILED MAY 2, IQMJRENEWED FEB-23.1918.

1,280,609 Patented 0051,1918.

2 SHEETS-SHEET x.

.l V/r/v aszs knew/#012- HTTOAf/MEYS B. D. WILLIS.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED MAY'L1914- RENEWED FEB. 23.1918.

1,280,609 Patented Oct. 1, 1918 2 SHEETSSHEET 2- .pq IIHIIIIIIIHI BERNARD n. WILLIS, orcIIIcAGmILLINoIs, AssIenon TO AUTOMATIC ELEc'imIo COMPANY, OE-CHIGAGO, I nINoIs, A CORPORATION or ILLINOIS.

Application filed m @1314, seiiirino, $5317. i

Be'it knownthat BERENARD a citizen of the-United States of America, i

and-resident of' chicagd, Cook county,fIllinois," have "invented '-'certain new: and useful Improvements in Automatic Telephone Sys-' "automatic tel'ephon isystems that' is, -systemsfin which one 'o'r more switchesar 1 ployed for establishing connectio'n between' subscribe'rs" lines. f

Onefof'th features of iiiy' invention re lates'to the provision of a"tlraificfltrunlgfrom which the ringing current is disconnected without reversing' the" current on the calhng line for -a'sufiicient interval or time tocause This' and otherobgects ofjmy invention the bperation of th e' measured service dey ice' will be more clearly understood ,by' reference to the accompanying drawings, inwhichl have illustrated'inyf iny'ention in connection with automatic switchesf" "of well-known types, [together with a ccit-ain' welF-knownj romrofmanun apparatus. My invention" is, teams; equally as well adapted forv use with jothe'r 'forms "of automatic switches and icord circuits, and the". present systcm is merely forfthe purpose of illustrating one specific embodiment of ay 1nyent1'on.

In the drawings Figures 1 and'2 represent a local circuit connection bctweenfa'calling "substation "A, and a called substation ,A, The" connection, is completed through the medium of the suhscribersindividuall switch C, 'thefs'elec tor switch E, the" connector switch H and the called subscrib'ers individual switch C" to the called substatio'n AC)" i The 's'ubscribePs'substation A is of any suitable or approved type and comprises the usual receiver 2, transinitter 3, switch-hook 4, ringer 5 and condenser 6. Being an automatic substation itis"also 'provided'with an impulse transmitter or callingfievice which is herein represented by a pa r of impulse springs 7 and 18 andanimpulse'wheel 9, is assumed to be controlled which latter I through the medium of'a finger hole dial (not-shown) in such a mauner'that the 1mo the cli'gitcalled.

iispebificatien of Letters Patent.

steamin r n ErrIoNE SYSTEM.

Patented Oct. 1, 1918.

Renewed February 23, 1918. Serial K0. 218,898.

' i The subscribers individual switch C is of the general type of subscribers individual switch shown in British patent to R. WV. James No. 26,301 of 1906, being, however, of the particular type disclosed in British patent to T. G. Martin No. 1-119 of 1910. This The magnet 11 comprises four windings, namely a pulldown winding 12, a cutoff or holding winding 13,"a line winding 1 and anauxiliary winding 15. The core of the magnet 11 is so constructed that the magnetic circuit of the'windings 12 and 13 is separate from that of the windings 14-and 15. The winding 12 operates both the plunger arm 10 and the armature 16, while the winding 13 is only strong enough to operate the cut-off armature 16 and to hold tlicqilunger arm 10 in its operated position. When the plunger arm 10 is operated, the plungevis forced into a bank of contact springs, forcing the springs 17, 18, 19 and 20 into engagement.

with the springs 21, 22, 23 and 2.4, respec tively, Although only one set of springs (1'(21 cl is shown, each line switch is pro. vided with a plurality of such sets, each set forming the terminal of a trunk line leading to a selector switch E. Each trunk line is connected in multiple with the corresponding springs of all the line switches of the group which is controlled by the master switch D. The switch C is controlled by the subscriber through the medium of the line relay 14, as will be hereinafter more fully The master switch D is of the same gan eral type as that disclosed in British Patent No. 26,301 of 1906, referred to above, being, however, of the particular type disclosed in 'said British Patent No. 1419 of 1910. The

function of the master switch, as is well known, is to maintain the plungers-of all the idle line switches in position to engage the terminal of an idle trunk line.

Associated with the individual v The first selector switch E is of the general type of selector switch disclosed in United States Letters- Patcnt No. 815,321,

granted March 13, 1906, to Keith, Erickson and Erickson, except that the so-called side i switch is omitted and the circuits are modi= known manner. .releesemagnet. The line relay e7 1s con- 38* fled to adapt the switch to operate in a; system in which it is controlled by impulses delivered over two sides of the line in series, as shown in BritishP-atent No. 10,376 of 1912, granted to T. G. Martin. v

The connector switch H (Fig. 2) is of the same general type or" connectorswitch as disclosed in United States Letters Patent No.1 815,176, granted March 18, 1 366, to Keith, Erickson and Erickson, the -'circ'uits, howyer, being modified toadapt the switch to opernte in a system in which the central oliice apparatus is controlled by impulses over the two sides of the line in series. Like the selector, the connector is provided with a shalt (not shown) carrying the wipers 36, 37 and 38, which shaft is controlled by the vcrtical'inagnet 39 and the rotary magnet l0, The usual side switch comprising the wipers e1, i2, i3 and is controlled by in the usual Wei- The magnet 16 is the usual the private magnet 4-5' nected with the line through the reversing springs of a so-called bridge relay 48,

through the windings of which latter relay the called line is provided with talking current. The rin ing relay 19 is the means through which the ringing current is applied to the-called line. At Q; there is shown a busy signaling machine which provides a to what is known a tra ic trunk, as shown at K, comprising the trunk conductors 52 and 53. Therefore, upon the subscriber at substation A attempting to call a, subscriber whose telephone has been. removed and the connector bank normals connected to the said tralllc trunk, he will signal an operator who will give him the necessary information. Bridged across this trunk is a'slow acting relay 141 which controls the circuit ofa second relay 143. These relays cooperate in a manner to be hereinafter more fully described to cut 0d the ringing current from the line without causing the operation of the meter on the calling line, as it is not desirable that a call be charged to the calling subsu on.

The ElllDSllfitlulL having been given,

line armature 95.

shown at and the line switch G arb similar respects to the substation A and the line switch 0 except that the individual switch C is not shown equippedwith a meter M. f

F or'the purpose ofsupply ing current for operating ,the central oifipcx apparatus and for'talkin'g purposes thereis shown in the drawings a battery B having oneterminal grounded at G.

A' general descriptiom-of the apparatus substation A to the called substation A,

the number of which latter will be assumed to be 220; Since the automatic switching it will nowbe explained how connection is extended from the calling apparatus disclosed herein is in general well known in' the art,- and is described in the publications hereinaBove referred to, its 0 eration will-be explained. ina more or ess. 4

general manner. Upon the removal of the receiver from the switchhook at the sub station A preparatory to making a call, the

talking circuit of the substation is bridged across the line, conductors 75 and 76, whereby the circuit of the line relay'l of the line switch C'is' closed, thereby attractingt'he I The armature. 95, upon v beingattracted, closes a cirouitthrough the pull-down coil 12 in series with'the auxiliary winding 15. The, pull-down coil, upon energizing, attracts .t

e plunger arm 10 for force the plunger 'into'the bankof contacts to 24, inclusive. It also operatesthe cutoil" armature 16, thereby disconnecting-the 7 line winding 14 fromithe line. The arma' ture does not fall back immediately, however, owing to the fact that the winding 15 is still in series with the pull-down coil 12. Upon the together to short-circuit the auxiliary winding 15, makingthe some slightly slow actplunger arm 10 being at- I tracted, the springs '96 and 97 are brought ing. The armature 95 being slow to fall backallows sufiicie-nt time for a holding circuit to be closed in the switch ahead for, the cut-off or holding winding 13. The engagement of the springsv17 and 20 with the i V springs 21 and 24, respectively, extends the subscribers lines to the line relay 30 of the selector E. The line relay 30 of the selector E is thereupon energizedover a circuit ex tending from ground Gr through the lower** winding of said relay, 81 and 82, bank springs over the heavy conductor contact of springs 75 to and through,

24 and 20, thence 7 the substation A, back over the other side of the line through the left-liand-winding' of the meter magnet 50,:bank springs 17 and 21 springs 83 and 84 andthe the relay 30 to battery B. Theielay 30,

upper winding of .125 upon energizing, closesthecirc'uit of the slow acting relay 34', which in turn, upon energizing, closes a circuit; extending from groundfl through the contact of springs: 85, bank sprlngs 22 and 18 and the holding which deenergizes shortly after it is disconcted from the line. The energization of tie rjelay 34 also completes a circuitextending from ground G through the contact of springs] 85, bank springs 22 and 18, through the right-hand winding of the meter magnet 50 and springs 86 to battery B. The current in this winding is in opposition to. the current flowing through the line winding andthe magnet is therefore not operated at this time. Upon the operation of the switch C the connector private bank contacts of the calling line are rovided with a guarding potential extending from ground G through the contacts of springs 85, bank springs 22 and 18 and the conductor 87 to the said private bank contacts. Upon the closure of the springs 19 and 23 by the operation of the switch C the master switch D operates in a well-known manner to advance the plungers of the idle line switches to a position opposite an idle trunk line.

The calling subscriber now operates his calling device for the first digit 2 of the'called number, whereby the substation impulse springs 7 and 8 are separated twice momentarily, each time breaking the circuit of the selector line relay 30. The selector'thereupon operates in the well-known manner, and as described in the patents referred to, to step the wipers up to the second level and to then cause them to rotate automatically to find an idle trunk, which we will assume is the one extending to the connector H (Fig. 2.) The line relay 47 of the connector thereupon becomes energized and closes the circuit of the relay 110,,which in turn, upon energizing, completes a holding circuit extendingfrom ground Gr through the contact of.

springs 111, conductor 112 and the wiper 26 of the selector E to the spring 106. Here the circuit divides, one branch extending through the springs 106 and 107 and the relay 108 to battery, the other branch extending through the springs 33, springs 103, bank, springs 22 and'18, through the holding winding 13 of the line switch C and the right-hand winding of the meter magnet 50 to battery B. The relay 110 of the connector H also maintains a guarding ground potential upon the private bank contacts of the trunk line in the banks of the first selector switches E which have access thereto.

When the substation calling device is operated for the second digit 2, the circuitof the connector line relay 47 is broken twice. Since the relay 110 is slow acting it does not deenergize during the mo mentary interruptions of its cir uit by the relay 4?, so that each time the latter relay is denergized, a circuit is closed extending from ground G through the springs 116 and 115, springs 1'19 and 118,

relay 121, vertical magnet 39 and the side' switch wiper 41 (in first position) to battery B. The vertical magnet '39 receives imthe switch shaft wipers 36, 37 and 38 to a position opposite the secondalevel of bank contacts. The relay 121, which is included I in series with the vertical magnet, remains in its energized position during the entire time that impulses are being transmittedthrough it and operates to close the circuit of the private magnet 45. After the last impulse is delivered, the relay 121 opens the circuit of the private magnet, which, upon denergizing, permits the side switchto advance from first to second position. The movement of the switch wiper 11 from first to second position transfers the battery connection from the vertical magnet 39 to the rotary magnet 40. The calling subscriber now operates his calling device for the last digit 0,

in response to whioh'the connector line relay 47 operates to transmit ten impulses through the rotary magnet 40in series with the relay 121, whereby the shaft wipers are rotated over the contacts of the desired line. The relay 121 operates in response to this operation in the same manner as for the previous digit to cause the private magnet 45 to advance the side switch one more position that is, from second to third position-after.

the last impulse for the digit is transmitted.

By the engagement of the side switch wipers i3 and 1 1 with their third-position contact points, and by the energization of the bridgecut-oif winding 122 of the line switch G,

the line connection is finally completed with the calledv substation, as .shown by theheavy cut-01f winding 122 extends from ground G through the side switch wiper, 42 (in third position), wiper, 37, conductor 123 and the said'bridge-cut-ofi winding to battery B. The connection of ground G with. the connector private bank contacts of the called line over the circuit just traced provides the sa d contacts with a guarding potential to prevent thebusy line from being seized by. some other connector switch. By the en- 'gagement of the side switch wiper 4:1 with its third position contact point the circuit of the ringing relay 49 is closed. This circuit extends from ground G through the interrupt/er 124, relay 4.9, springs 125 and the said 3 side switch wiper to battery B. The ringing relay 49, upon energizing, disconnects the calling line from the called line and bridges the ringing current generator R across subscriber his line is provided with talking 70 pulses overthis circuit and operates to raise 105 conductors. The circuit' for the bridge- I &

current through the windings of the back bridge relay 48 of the connector switch, which relay, upon energizing, closes the circuit of the ringing cut-01f relay 126. The said circuit extends from ground G through the sideswitch wiper 12, springs 12'? and the relay 126 to battery B. The relay 126, upon energizing, interrupts the circuit of the ringing relay 49 -the springs 125 and closes a locking circuit for itself through thesprings 128 independent one another and the armature is thereby atfollowing manner.

tracted to operate the meter to registerthen call.

-After the conversation is completed, the connection is released by the hanging up of the receiver at-the calling substation in the When the receiver at the substation A isvrestored to the switchhook, the separation of the hook-switch springs 77 and 78 destroys the energizing circuit of the'eonnector line relay 47. The relay 47 thereupon deenergizes and opens the circuit of the relay 110. Therelay 110, upon deenergizing, opens the holding circuits of the relays 18 and 108 of the line switch C and the selectofi E, respectively, at the springs 111 and closes the circuit of the connector release magnet 418- The latter circuit extends from ground G through the contacts of the springs 116 and 115, springs 119 and 120, ofi-normal springs 129 and the release magnet 16 to battery B. The magnet 46, upon energizing, restores the connector side switch andswitch shaft to normal position and its own circuit is interrupted at the springs 129 when the shaft reaches its lowest position. The deenergization of the relay 108 of the selector E closes a circuit through its release magnet 31 at the springs 91. This circuit extends from ground G through the springs 88 and 89, springs 91, springs 93 and 94C, springs 32 and the magnet 31 to battery B. The magnet 31, upon energizing, restores the selector to normal and its own circuit is broken at the springs 32 when the switch shaft reaches its lowest position. The deie'uergization of the winding '13 of the line switch C permits the plunger arm 10 to return to normal position.

If the called line is busy there will be a guardinglpotential upon the connector private bank contact, just as explained in connection with the line switch C. The connector private wiper, upon engaging this guardbattery B. The magnet 625 thus stays ener-. gized and holds the side switch in second position and disconnects the back-bridge re-' lay 48 from the line wipers. The relay 51, upon energizing, opens the circuit of the ro tary magnet 39 to prevent further rotation and closes a locking circuit for itself and the magnet 5-through the springs 132 and 181 independent of the ground at the private wiper. The engagement of the springs 135 serves to close a circuit for the busy tone,

which circuit extends from the busy machine Q, through, said springs, side switch wiper 1% (in second position), over the conductor 7 114 to and'through the substation A, return conductor 113 and the upper winding of the relay 17 to battery B. The calling subscriber, upon receiving the busy signal, hangs his receiver upon the switch-hook, thereby releasing the connection in the manner above described.

iVhenever a telephone is removed from service, or is temporarily disconnected for any reason, the lines leading to the central exchange are disconnected and the connector bank contacts are connected to the conductors 52 and 53 in the same manner that the connector bank contacts 139 and M0 are shown in Fig. 2. The conductors 52 and 53 terminate in a group of relays K situated at an information desk or manual operators board. It will now be explainedhow the substation A, in attempting to call a substation (not shown), will effect connection with the operator at the said manual board and -receive the necessary information without having the call registered upon his meter M. As soon as the calling substation has caused the line wipers 36 and 38 of the connector H to make contact with the bank contacts 139 and 1 10, the relay 1&1, which is bridged across the conductors 52 and 53, wiil immediately energize, or as soon after as the ring ing relay 49 deenergizes. The reiay 141 is of high resistance and does not permit suitioient current to iiow through its winding for the back-bridge relay 48 to operatively energize. Also, the said relay lail will not energize when the ringing relay i9 is energized, as the said relay is not responsive to ringing current. The relay 14:1, upon energizing, closes a short-circuit hcross the conductors 52 and SS-atthe springs; 1 12 and at the same time closes a circuit through the relay 1 13, which, upon energizing, removes the short-circuit across said conductors at the springs 14A- an instant iater. A further 6 vices having different time constants, a reresult of the energizing of the relay 141 is to. close a circuit through the signal' lamp 145.

This circuihextends from ground G through the contact of springs 146, springs 1&7 and the lamp 145 to battery B. The

short-circuiting of the conductors 52 and for an'instant causes the back-bridge relay 48 to energize for an instant. and cut off the ringing current, as hereinbefore described, but it is not held energized long enough to allow the meter M to be operativ ely energized. The operator, noticing the lamp 145 glowing, immediately operates the key K,

bridging her head set through the condenser.

connection w th automatic switches andv manual apparatus of a particular character, it will, of course, be understood that I do not wish to be limited to the exact construction shown and described, but that various changes and modifications will readily sug gest themselves to those skilled in the art and come within the spirit of my invention.

' What I claim as my invention Tis:

1. In a telephone system, a subscribers line, a trunk line, a connector switch accessible to said line for connecting with said trunk line, automatic ringing equipment in said connector switch, a measured service device associated with said subscribers line, a device in said connector for preventing the operation of said equipment, said devices having diiierent time constants,-a relay in said connector for operating said devices, a normally open bridge across said trunk, a

pair of relays, one for closing said bridge 1,

and the other foropening said bridge, and

means for operating the relays of said pair in rapld succession upon the connection with said trunk by said connector, whereby a circuit is closed momentarily for the relay f in said connector to operate one of said de vices without operating the other.

2. In a telephone system, a subscribers line, a trunk line, a connector switch accessible to said line for connecting with said trunk line, automatic ringing equipment in said connector s itch, a measured service device associated with said subscribers line,

'a device in said connector for preventing the operation of said equipment,.said desaid devices,

lay in said connector Ior operating said do-- vices, a high resistance 'relayinj r dge of said trunli line and adaptedto .be" connected in series'with the said first relay" upon the seizurebfthe trunk line by said connector, said first relay'remainin'ginopera .e', means controlled by said second relay for closing a low resistance bridge across said trunk line to operate said 'fi'rst relay, "and means for opening said lowresis tance bridge to deenergize said'first relay before th slower of said devices'has operated In a' telephone system, afsubscribers line, a trunk line, a connector switch. accessible to said line for connecting with said trunk' line, automatic ringing equipment in said connector switch, "a measured service device associated with said subscribersline, a de'vicejin said connector 'forpreventing the operation' of said equipment, s'aid devices having different time constants, a relay in said connector for operatingsaid de vices, .a high-resistance relay in bridge of said trunk line and adapted to be connected in series with the said first relay upon the seizure of the trunk-line by said connector, said first relay remaining inoperative, means controlled by said second'rela'y for closing a low resistance bridge across said trunk line to operate'saidfirstrelay to operate one of'said devices, and means for opening saidlow. resistance'bridge todeenergize said first relay-before the other of said'devices has operated. i i 4.-In a 'telephone'systeni, a"'subscribers line, a trunk lin'e, a-co'nnector switclraccessible to s'aid'line 'forconnectingwith said trunk line, automaticringing equipment in said connector switcln a' measured service device associated with saidsubscribers line, a device insa-id connector for preventing the operation of said equipment, said devices having different time-constants, a relay in sand connector for operating sald devices, a

high resistance relay in'bridge of s'aidtrunk line and adapted to "be connected in series 'first rel "upon the seizure with the sa' (1 e by'said fconn'ectoiy'sai'd first relay remaining inoperative, means controlled by "said secondmelay for-closing a "low resistance bridge" ess trunli line d first relay to e emteone of v andrelay 'co'ritroll'edby Qsaiu high (resistance rejlay ior Iopening said low resistance bridge to deenrgne said first relay before the other of said devices has operated.

5. In a telephone system, a subscribers line, a trunk line, a connector switch accessible to said line for connecting with said trunk line, automatic ringing equipment in said connector switch, a meter associated with said subscribers line, a relay in said .connector for preventing the operation of said equipment, said relay operatto operate ing the relays of'said ing more rapidly than said meter, a second relay in said connector for operating-said "meter and for initiating the operation of said first relay,'-a normallyopen bridge across saidtrunk,;'a pair of relays, one

for closing said bridge -and the-other for opening saidbridge, and means "for operatsion upon the connect on with said trunk line by said connector, wherebya. circuit is closed momentarilyfor the said second relay without operating'said meter.

6. In a telephonesystem, a subscribers line, a trnnkline, a connector switch acces-- sible to said-hne for'connectlng wlth sa1d trunk line; automatic ringing equipment in said connector switch, a'met'er'associated with said subscribers line, a relay in said connector for preventing the operationof said equipment," said' relay operating more rapidly than saidineter, a second relay insaid connector for operating said meter and i for initiating'the operation of said first re lay, a high resistance relay in bridgefof said trunk line and adapted to'be' connected in series withIthe said second relay when said hnes are connected by said connector, said second relayremaining inoperative, means controlled bysaid high resistance relay for closlng a low reslstance bridge across said trunk line to operate said'second relay, and means for immediately 'opening'said low resistance bridge to deenergize said secondrel y whereby said first relay may be-operated without actuating said meter.

. 7. In a telephone systeni, the combination with a calling"snbscribers'line and a measur'ed service device associated therewith, of

;a trunk line leading to an operators posi- 40' ,o ""and' trunk line, automatic ringing equiption, a link circliit rc'onnecting said line 'ment associated; with said'link circuit, a relay associated with said link for prevent- --.ing the operation" of said ringing equi ment, a second relay'associated with said "link for operating said device andfor initiating the operation of-said first relay, said first relay adji sted to operatevmore quickly then said device,-'a normally open 'bridge acrosss'aid trunk,ra'pair of relays, one for closing said bridge and thejother for opening. said bridge, and-means for operating the relays of said 7 pair in rapid succession fnpon the connection of saidxlink circuit to air in rapid successaid trunk line, whereby a circuit is closed momentarily {or the said second relay to operate said first relay without operating said device. 4

8. In a telephone system, the combination.

with aicalling subscribers line andv a Incas ured; service device associated therewith, eta:

trunk'line to an operatnrs position, a link circu t for connecting said line and trunk line, automatic ringing equipment associated with said link circuit, a relay associated.

with said link for preventing the operation of said ringing equipment, a second relay associated with'said link for operating said device and for initiating the operation of sa'idfirst relay, said iirst' relay adjusted to operate more quickly than said device, a high resistance relay in bridge or said trunk line and adapted to be connected in series with the said second relay when said lines are connected by said link circuit, said second relay remaining inoperative, means controlled by said high resistance relay for closing a low resistance bridge across said trunk line to operate said second relay, and

means for immediately opening said low resistance bridge to de'ner'gize said'second relay, whereby said first relay may bev operated without actuating said device.

9. In a telephone system, the combination with a subscriberslline and ameasuredservice device associated therewith, of a trunk line, a connector switch, means for operating said switch over said line to connect with said trunk line, a source of ringing current, a relay in said connector for applyingsaid source to said trunk line when connection is established therewith, a second relay in said connector for preventing the operation of said first relay, a third relay insaid connector for operating said device and for initiating the operation of said second relay, means in said. trunk for clos- 

